Reproducibility of phalanx osteosonography and relation with forearm peripheral quantitative computed tomography: single finger versus average measurement on the last four fingers

The aim of this study was to evaluate the in vivo short-term reproducibilit y of amplitude-dependent speed of sound (AD-SOS) measured at the proximal p halanx, using an Igea DBM Sonic 1200 device, as well as its relationship wi th bone mineral density of the ultradistal radius, assessed using periphera l quantitative computed tomography (pQCT). In particular, the authors wishe d to evaluate whether average measurements on the last four fingers, as rec ommended by the manufacturer, yielded or not more information than measurem ents on one single finger. For the precision study, the authors carried out phalanx osteosonography ten times once every other day in ten healthy youn g women. To compare with pQCT of the radius, 37 women referred for screenin g of osteoporosis (mean age 60 years) were studied. AD-SOS was reported for each finger separately, as well as an average; pQCT (XCT 960 Stratec) yiel ded trabecular (BMDt); cortical (BMDc); and total (BMDtot) bone mineral den sities, as well as the cortical area (A(c)). The reproducibility of AD-SOS was significantly higher for the middle finger (mean coefficient of variati on (CV) 1.1%) and the index than for the ring and small (mean CV 2.7%) fing er. The middle finger consistently showed the best correlations with pQCT v ariables; the relationships involving BMDc (r = 0.54), BMDtot (r = 0.62) an d A(c) (r = 0.61) were stronger than that with BMDt (r = 0.34). The authors conclude that phalanx AD-SOS is moderately correlated with BMD of the ultr adistal radius-at least when it includes the cortical component-and that re porting AD-SOS for the middle finger-instead of an average value-improves t he reproducibility and possibly the relevance of phalanx osteosonography. ( C) 1998 Elsevier Science Ireland Ltd. All rights reserved.